Integration of in-well wetmate esp motor connector with high pressure hydraulic line

ABSTRACT

A method includes placing an apparatus in a subsea wellbore ( 102 ), and hydraulically connecting the apparatus with an external hydraulic fluid source ( 107 ). The apparatus of this method includes a pump ( 103 ), a motor ( 105 ), a pressure intensifier ( 109 ), and a hydraulic fluid port ( 110 ). The motor ( 105 ) is configured to drive the pump ( 103 ). The pressure intensifier ( 109 ) is configured to maintain pressure of the hydraulic fluid in the motor at a predetermined level. The hydraulic fluid port ( 110 ) is configured to provide hydraulic fluid to the pressure intensifier ( 109 ) by mating with the external hydraulic fluid source ( 107 ) when the apparatus is in a hydrocarbon producing wellbore. The apparatus is dimensioned for lowering and retrieving through the string of production tubing ( 112 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/270,753, filed Dec. 22, 2015, which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates installation and operation of electrical submersible pumps (ESPs), and in particular to a permanent installation of an ESP.

BACKGROUND

A variety of fluid lifting systems pump fluids such as hydrocarbons from wellbores to surface holding and processing facilities. Commonly, one of a number of various types of downhole pumping systems pumps subterranean formation fluids from a particular wellbore to surface collection equipment for transport to processing locations.

One such system is a submersible pumping assembly that is supported immersed in production fluid within the wellbore. The submersible pumping assembly has a pump and a motor to drive the pump to pressurize and pass the production fluid through production tubing to a surface location. A typical electric submersible pump assembly (ESP) includes a submersible pump, an electric motor and a seal section interdisposed between the pump and the motor. The purpose of the seal section is to protect the motor from contamination as the production fluid usually contains deleterious substances such as particulate solids and other debris from the formation. Much research focuses on improved seal sections to prevent or at least reduce environmental contamination of the motor. Other efforts have involved development of motors that function even with contaminants present. Nonetheless, over time, ESPs still fail, most frequently from contamination. In some environments, such as deep-sea applications, the retrieval and remediation or replacement of an ESP is very expensive.

Thus, there is a need for manner of effectively preventing deleterious substances, such as particulate solids and other matter contained in formation fluids, from entering the motor where such contaminants can interfere with the efficient operation of the motor and can reduce the operational life of the motor.

SUMMARY

An apparatus includes a pump, a motor, a pressure intensifier, and a hydraulic fluid port. The motor is configured to drive the pump. The pressure intensifier is configured to maintain pressure of hydraulic fluid in the motor at a predetermined level. The hydraulic fluid port configured to provide hydraulic fluid to the pressure intensifier by mating with an external hydraulic fluid source when the apparatus is in a hydrocarbon producing wellbore. The apparatus is dimensioned for lowering and retrieving through the string of production tubing.

A method includes placing an apparatus in a subsea wellbore, and hydraulically connecting the apparatus with an external hydraulic fluid source. The apparatus of this method includes a pump, a motor, a pressure intensifier, and a hydraulic fluid port. The motor is configured to drive the pump. The pressure intensifier is configured to maintain pressure of the hydraulic fluid in the motor at a predetermined level. The hydraulic fluid port is configured to provide hydraulic fluid to the pressure intensifier by mating with the external hydraulic fluid source when the apparatus is in a hydrocarbon producing wellbore. The apparatus is dimensioned for lowering and retrieving through the string of production tubing.

Another method includes placing an apparatus in a subsea wellbore and hydraulically connecting the apparatus with an external hydraulic fluid source. Pressure of the external hydraulic fluid source acts to maintain pressure of hydraulic fluid in a motor of the apparatus at a predetermined level. The apparatus includes a pump, the motor, and a hydraulic fluid port. The motor is configured to drive the pump. The hydraulic fluid port is configured to provide hydraulic fluid by mating with the external hydraulic fluid source when the apparatus is in a hydrocarbon producing wellbore. The apparatus is dimensioned for lowering and retrieving through the string of production tubing.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of an apparatus, in accordance with the present disclosure, deployed in a wellbore.

FIG. 2 is a flowchart of a method of using the apparatus of FIG. 1, in accordance with the present disclosure.

DETAILED DESCRIPTION

FIG. 1 shows an apparatus 101 (e.g., an ESP or other electric pump) installed in a hydrocarbon producing wellbore 102 (e.g., an onshore well, an offshore well, a deep sea well). Apparatus 101 may include a pump 103, an optional seal 104, and a motor 105 that drives the pump. Pressurized hydraulic fluid is present in the apparatus 101 for lubrication and cooling, as well as for preventing intrusion of production fluid 106 into the motor 105. The hydraulic fluid may be mineral oil, glycol based, transformer oil, or other similar fluids. A motor housing (not shown), pressure, and the seal 104 may protect the motor 105 from the intrusion of damaging production fluid 106. However, over time, the hydraulic fluid will begin to leak into the environment, due to wear, vibration, age, etc. The leakage rate is dependent on fluid properties, differential pressure, the transient operating conditions of the pump, and the tightness of the seal(s).

Traditionally, once enough hydraulic fluid has left the apparatus 101, the pressure therein will drop to that of the production fluid 106, allowing for intrusion of production fluid 106 into the motor 105, eventually causing the apparatus 101 to fail. However, the presently disclosed design may maintain the pressure of the hydraulic fluid indefinitely by providing an external hydraulic fluid source 107 connected to the apparatus 101 via a hydraulic fluid conduit 108. The external hydraulic fluid source 107 may be located on the host and connect via umbilical or the external hydraulic fluid source 107 may be located at the mud line. In this manner, even when the seal 104 fails and hydraulic fluid leaks, pressure can be maintained at a level sufficient to prevent the deleterious effects of production fluid 106 entering the motor 105.

Thus hydraulic fluid flows to the apparatus 101 for distribution to the motor 105 and or the pump 103 for lubrication internal structures, such as pump rotor bearings, seals and timing gears. The pressure in the lubrication fluid circuit of the motor 105 and pump 103 may thus be maintained above the pressure of the production fluid displaced through the pump, in order to prevent intrusion of process fluid and particles into pump hearings, seals, and timing gears.

The mechanism for maintaining a predetermined level of pressure of hydraulic fluid in the motor 105 may include a pressure intensifier 109 such as is described in U.S. Pat. No. 9,097,267 or other similar device for providing a boost to the pressure in the motor 105. However, in the present apparatus 101, the pressure intensifier 109 may recharge without removing the apparatus 101 from the wellbore 102. Instead, a hydraulic fluid port 110 may provide hydraulic fluid to the pressure intensifier 109 such that the pressure intensifier 109 can adequately maintain pressure of hydraulic fluid in the motor 105 at the predetermined level.

A string of casing 111 may be cemented to an inner surface of the wellbore 102, and a string of production tubing 112 may be located within and generally coaxial with casing 111 to form an annulus 113 between casing 111 and production tubing 112. A packer 114 (e.g., a swab cup) may be located at a lower end of production tubing 112 and may lie between casing 111 and production tubing 112 to prevent production flow or other fluids from entering annulus 113. A check valve 115 in the lower portion of production tubing 112 may prevent fluid loss from fluid flowing downward. Check valve 115 may also allow for pressure-assisted removal of apparatus 101. An additional swab cup, or other type of packer 116, may be located between pump 103 and the inner surface of production tubing 112. Packer 116 may be a lip seal and may be run with apparatus 101. Packer 116 may allow upward flow while preventing downward flow therethrough. As apparatus 101 moves into place, packer 116 may slide on the interior of production tubing 112, allowing displaced fluid to flow past packer 116.

Apparatus 101 may be assembled by securing a lower end of pump 103 to an upper end of seal 104 and securing a lower end of seal 104 to an upper end of motor 105. A running tool (not shown) may releasably engage a neck 117 on the upper end of pump 103, such that production fluid 106 may flow out of neck 117. The apparatus 101 may then move into the wellbore 102 with the running tool on a line (not shown), such as coiled tubing or cable, through production tubing 112 until the apparatus 101 and corresponding elements reach the desired depth. The running tool and coiled tubing may then be retrieved. Apparatus 101 may pass through an orienting sleeve 118 where it may rotate by engagement with a helical shoulder 119 that may assist in rotationally aligning apparatus 101 to the required orientation for positioning within a mating profile 120. The running tool may have a swivel, or other bearing, to allow apparatus 101 to rotate during installation without rotating the coiled tubing.

One or more wet-mateable hydraulic fluid connectors 121 may provide hydraulic fluid to motor 105. Hydraulic fluid connector 121 may affix to production tubing 112 and lie fully within annulus 113 or may slightly protrude within production tubing 112. The hydraulic fluid connector 121 may connect to a hydraulic fluid conduit 108 that feeds hydraulic fluid from an external hydraulic fluid source 107 to hydraulic fluid connector 121. Hydraulic fluid conduit 108 may extend alongside and be strapped to production tubing 112. Hydraulic fluid conduit 108 may provide high-pressure (e.g., in the range of 15-45 psi higher than the wellbore pressure) hydraulic fluid to the apparatus 101. Apparatus 101 may include a hydraulic fluid port 110 positioned for mating with hydraulic fluid connector 121. In this illustration, outer hydraulic fluid connector 121 engages the hydraulic fluid port 110. The wet-mateable hydraulic fluid connectors 121 may be analogous to the connections described in U.S. Pat. No. 8,381,820, although modifications would be necessary to adapt the technology described therein to provide hydraulic fluid to the intensifier 109 of the present disclosure. In addition to hydraulic connections, electrical connections may be provided via a connector and line configured for such purpose. For example, the hydraulic fluid connector 121 and the hydraulic fluid port 110 may also include electrical connections and the hydraulic fluid conduit 108 may run alongside an electrical cable.

Referring now to FIG. 2, a method of using the apparatus 101 described above may include various steps. At step 201, the apparatus 101 may be placed in the wellbore 102. Next, at step 202, the apparatus 101 may be hydraulically connected to the external hydraulic fluid source 107. Alternatively, hydraulically connecting the apparatus 101 with the external hydraulic fluid source 107 may occur prior to placing the apparatus 101 in the wellbore 102. In either event, the step of hydraulically connecting may be accomplished via the hydraulic fluid connector 121. At step 203, the method may further include maintaining pressure of the hydraulic fluid in the motor 105 at a predetermined level via the pressure intensifier 109. This may involve actively measuring and making adjustments or alternatively passive means such as a pressure limit valve. In either event, over time, the pressure intensifier 109 loses pressure without introduction of additional pressure andior hydraulic fluid. Therefore, at step 204, it is determined whether the pressure in the pressure intensifier 109 has dropped below an intensifier pressure level or that the level in the intensifier 109 is low. Again, this may involve either active or passive methodology. In any event, at step 205, hydraulic fluid is provided to the pressure intensifier 109 via the hydraulic fluid port 110, which is fed from the external hydraulic fluid source 107. In addition to the above steps, the external hydraulic fluid source 107 may be used to flush the motor 105, clearing any debris that may have entered, despite precautionary measures having been taken. Similarly, the external hydraulic fluid source 107 may be used to flush the wat-mateable connection during mate-up. Alternatively, the external hydraulic fluid source 107 may be used to flush the motor 105 without performing most of the steps noted above. For example, once the apparatus is placed at step 201 and hydraulically connected at step 202, the remaining steps may be omitted and only flushing may occur. Alternatively, flushing may occur in conjunction with the connecting step 202, to flush fluids during makeup of the connection.

In another example, the external hydraulic fluid pressure may act directly and the pressure intensifier 109 may not be required. In such instance, the method may be as described above but without the inclusion of the pressure intensifier and the addition of pressure of the external fluid source acting to maintain pressure of hydraulic fluid in the motor at a predetermined level.

The advantages of using the present invention may include a permanently deployed source of high-pressure hydraulic fluid replenishment. By permanently deploying a source of high-pressure hydraulic fluid, the cost and difficulty of removing the pump assembly to remediate wear caused by insufficient hydraulic fluid may be mitigated. 

1. An apparatus comprising: a pump; a motor configured to drive the pump; a pressure intensifier configured to maintain pressure of hydraulic fluid in the motor at a predetermined level; and a hydraulic fluid port configured to provide hydraulic fluid to the pressure intensifier by mating with an external hydraulic fluid source when the apparatus is in a hydrocarbon producing wellbore; wherein the apparatus is dimensioned for lowering and retrieving through the string of production tubing.
 2. The apparatus of claim 1, wherein the source of hydraulic fluid external to the apparatus comprises a hydraulic fluid connector of a string of production tubing in the hydrocarbon producing wellbore.
 3. A method comprising: placing an apparatus in a subsea wellbore, wherein the apparatus comprises: a pump; a motor configured to drive the pump; a pressure intensifier configured to maintain pressure of hydraulic fluid in the motor at a predetermined level; and a hydraulic fluid port configured to provide hydraulic fluid to the pressure intensifier by mating with an external hydraulic fluid source when the apparatus is in a hydrocarbon producing wellbore; wherein the apparatus is dimensioned for lowering and retrieving through the string of production tubing; and hydraulically connecting the apparatus with the external hydraulic fluid source.
 4. The method of claim 3, wherein hydraulically connecting occurs prior to placing the apparatus.
 5. The method of claim 3, wherein hydraulically connecting is accomplished via a hydraulic fluid connector.
 6. The method of claim 3 further comprising maintaining pressure of the hydraulic fluid in the motor at the predetermined level via the pressure intensifier.
 7. The method of claim 6, further comprising providing hydraulic fluid to the pressure intensifier via the hydraulic fluid port.
 8. The method of claim 7, wherein providing hydraulic fluid occurs after a determination that the pressure in the pressure intensifier has dropped below an intensifier pressure level.
 9. The method of claim 3 further comprising using the external hydraulic fluid source to flush the motor.
 10. The method of claim 8, wherein providing hydraulic fluid occurs after a determination that the level in the intensifier is low. 